C. M. Warren on the Volatile Hydrocarbons. 219 
taken at 160°C. Example: cumole (from cuminiec acid) has the 
formula CisH,2; hence it contains C2 less than oil of turpentine; 
therefore 35°°5 must be deducted from 160° (the boiling-point of 
oil of turpentine,) which leaves 124°°5; but as the cumole con- 
tains 2H, less than oil of turpentine, 15°x2=380° is to be added 
to the above remainder; thus 124°-5+30°=154°%, the calcula- 
ted boiling-point of cumole. Gerhardt’s direct determination 
was 153°, which very nearly coincides with his theory. : 
It would be foreign from my purpose on the present occasion 
to consider these different hypotheses, or even the empirical law 
of Kopp, beyond their special relation to the boiling-points of 
the hydrocarbons, and such other series, derivatives from the 
hydrocarbons, as have been made the subjects of my own experi- 
ments. Anything more than this would be merely speculative. 
The want of more accurate determinations of boiling: points as 
essential to safe and reliable deductions and generalizations on 
The need of this 
this question in its different bearings, which, from its importance, 
It clearly meri 
roceed with these researches, 
